Princeton Election Consortium

A first draft of electoral history. Since 2004

Meta-Margins for control: House D+1.0% Senate R+4.2% Find key elections near you!

Discover Your Inner Federalist! Using State Constitutions To Stop Gerrymandering

March 29th, 2019, 11:56pm by Sam Wang

Update, July 17, 2019: The Supreme Court didn’t act to curb partisan gerrymandering. But there’s a second route to justice: state courts. In Slate, the Princeton Gerrymandering Project’s Ben Williams reports. To read about this idea, our forthcoming article [SSRN link] in the University of Pennsylvania Journal of Constitutional Law spells it all out.

→ 1 CommentTags: Redistricting

Partisan gerrymandering and the Chief

March 26th, 2019, 8:28am by Sam Wang

Today, the Supreme Court hears two partisan gerrymandering cases, a Republican offense in North Carolina (Rucho v. Common Cause) and a Democratic offense in Maryland (Benisek v. Lamone). The outcome likely hinges on the vote of Chief Justice John Roberts (or Associate Justice Brett Kavanaugh…developing…).

In the Atlantic, I review how far the math has gotten in providing objective standards. Researchers have done great work. Even if the Court doesn’t use it, it’s still available for the use of state courts.

→ Post a commentTags: Redistricting is live!

March 21st, 2019, 8:45pm by Sam Wang

Until now, politicians had a monopoly on the data needed to draw district maps. The Princeton Gerrymandering Project’s data specialist Hannah Wheelen is helping to change that. Hannah oversees data collection for, our tool to let citizens talk back to redistricters. She’ll talk about our overall approach, especially our recent efforts in Virginia. We plan for OpenPrecincts to go nationwide in time for 2021 redistricting.

Also, we need partners nationwide. To get involved, write to us at! – Sam

When it comes to redistricting, the public is on the wrong end of a tilted playing field. I joined PGP to help level that playing field. This requires lots of data, including (i) where voting precinct boundaries are; and (ii) precinct election results and demographic information. You’d think this information would be publicly available – but it’s not.

US elections are administered locally, so the collection process is difficult. We have to inquire around a state for maps by email, phone, or sometimes even in person. Here is a paper map hanging on a wall in a trailer in rural Virginia. My PGP colleague Ben Williams put aside his legal analysis and drove the windy roads of the Blue Ridge Mountains to take its picture. There is only one copy of the map. They don’t even have cellphone service out there!

At PGP, we turn pictures like this into usable data. We convert everything to computerized shapefiles, marry it to election data, and release it freely to to the public. Our portal, ​(sneak peek below), allows us to coordinate with data teams around the country, boosting their efforts and generating a resource bigger than any one group can do alone.

We have national dreams: we plan to hit all 50 states, the District of Columbia, and Puerto Rico in time for 2021 redistricting – and earlier in hotspots of legislation and activism. This will be the first integrated national database of its kind. We invite you to pitch in time to collect data, donate to fund your state’s collection efforts, or browse states like Virginia that are already completed.

Visit our beta site of today!

→ 2 CommentsTags: Redistricting

On this morning with Michigan SoS Benson!

March 21st, 2019, 9:44am by Sam Wang

Tune in right this minute!

Sorry, over now…fun and quick. However, you can still listen here.

Michiganders, be on the lookout for chances to join the new Redistricting Commission!

→ Post a commentTags: Redistricting

Princeton brief in Rucho v. Common Cause

March 8th, 2019, 5:26pm by Sam Wang

Wesley Pegden of Carnegie-Mellon University, Jonathan Rodden of Stanford University, and I joined forces on an amicus brief (PDF). We offered the court our views on the federal partisan gerrymandering case from North Carolina, Rucho v. Common Cause (this link goes to all the other briefs as well). We describe to the court how the various tests of partisan unfairness fall into two big categories: inequality of opportunity and inequity of outcome. We furthermore describe how the drawing of many alternative maps can do both jobs.

Wesley Pegden is best known in redistricting circles for a theorem he and co-authors published last year regarding the Monte Carlo Markov chain approach. This approach finds many (typically billions) of maps that are made by making small changes to a candidate map. He showed that if the candidate map is most extreme of N such maps, it must be in the O(1/sqrt(N)) range of maps that can be reached by MCMC. He, Moon Duchin, and Jonathan Mattingly (expert in the N.C. case) have all been applying this approach to redistricting with great effectiveness.

Jonathan Rodden has a long history of drawing ensembles of maps. Using older methods, he and Jowei Chen (now at University of Michigan) have used a random-seeding approach to draw hundreds of maps, not related to one another, to explore a wide range of possibilities.

My own contribution to this brief was to point out that despite the proliferation of map-based and simpler numerical-measurement tests, they fall into two big buckets from a legal standpoint: inequality of opportunity and inequity of outcome. That was the subject of our recent prizewinning entry in the Common Cause contest. Examples include lopsided wins (test of opportunity; applies to N.C.) or uniform wins (again a test opportunity; applies to Maryland). MCMC tests both opportunity and outcome.

We were very ably represented by Tacy Flint. She is a former clerk of Richard Posner and of Stephen Breyer, and she led a legal team at Sidley Austin. All in all, it was a dream team of co-authors and counsel. It was a pleasure to work together!

→ 3 CommentsTags: Redistricting · Supreme Court

NJ Redistricting Forum at Princeton University – postponed to Tuesday February 26th

February 20th, 2019, 12:18pm by Sam Wang

The redistricting forum scheduled for tonight at Princeton University is postponed on account of weather. It’s now resecheduled for next Tuesday, February 26th. The location’s the same, Maeder Hall. Here’s the flyer.

This is an event hosted by the League of Women Voters New Jersey and FairDistrictsNJ. It’s part of a series.

See you next week, and stay warm!

→ 1 CommentTags: Redistricting

Meet the Woo Students!

February 18th, 2019, 4:20pm by Sam Wang

In our recent report on Michigan’s new commission, the main movers were M.P.A. students of the Woodrow Wilson School for Public and International Affairs. Above, meet Tarrajna, Henri, and the rest and learn how they did it!

→ 2 CommentsTags: Redistricting

Laboratories of Democracy Reform: State Constitutions and Partisan Gerrymandering

February 15th, 2019, 10:46pm by Sam Wang

Uncertain about whether the Supreme Court will do anything about partisan gerrymandering? We have something for you. Rick Ober, Ben Williams, and I have completed a manuscript, “Laboratories of Democracy Reform: State Constitutions and Partisan Gerrymandering.” It’s available here on SSRN and here as a PDF.

In our article, we argue that partisan gerrymandering can be curtailed on a local basis using state law and constitutions. The intellectual framework was laid out by Chief Justice John Roberts and Justice Elena Kagan in their decision and concurrence in Gill v. Whitford. And even if they themselves don’t use it, this framework is available for state courts to use under state law.

Their logic is built upon the concepts of equal protection and freedom of association: voters should not be penalized individually (Roberts; equal protection) or in the aggregate (Kagan; freedom of association) for expressing partisan views. As it happens, these provisions are found in state constitutions across the nation.

So long as it doesn’t conflict with federal law, a state court-based ruling is not subject to review in federal court. And generally, it is possible for state courts to provide for more rights than federal courts do. So a new state protection can be reconciled with a wide range of possible actions by the Supreme Court on the North Carolina and Maryland cases currently before it. We give dozens of examples where states used their own law or constitution to overturn a map. Finally, we suggest states where conditions may be right for a local approach, including North Carolina and Wisconsin.

Unleash your inner Federalist!

→ Post a commentTags: Redistricting · Supreme Court

On Michigan Radio

February 11th, 2019, 10:04pm by Sam Wang

Today I spoke with Cynthia Canty of Michigan Radio about the road ahead for the Michigan redistricting commission. Great conversation – take a listen!

Comments Off on On Michigan RadioTags: Redistricting

A Commissioner’s Guide to Redistricting in Michigan

February 4th, 2019, 12:00pm by Sam Wang

Today we’re releasing a detailed report on Michigan’s new Independent Citizens’ Redistricting Commission!

In November, Michigan voters overwhelmingly approved an amendment to their state constitution to remove the power of the state legislature to draw legislative and Congressional district boundaries. The vote was a victory for those seeking to end gerrymandering, but it’s the only the beginning of a process.

The Princeton Gerrymandering Project has been helping master’s of public policy students at the Woodrow Wilson School to prepare a report highlighting best practices in forming the commission and in executing its constitutional duties. The report is titled A Commissioner’s Guide to Redistricting in Michigan. You can read it here, or download a PDF.

Among our major findings: [

→ Post a commentTags: Princeton · Redistricting